This invention relates to styrenic polymer foams having improved flammability characteristics and to a composition and process for the preparation thereof.
Extruded foams of styrenic polymers are known and are highly desirable for many applications such as for use as thermal insulation, packaging and the like. In such applications, it is generally desirable that such styrenic polymer foams exhibit the best practicable flammability characteristics (i.e., the lowest practicable propensity to ignite and/or to support combustion once ignited). Accordingly, a number of prior art approaches for improving the flammability characteristics of styrenic polymer foams have been suggested. Such approaches include the incorporation into such foams of relatively large quantities of halogen-containing compounds as flame retardant components therein; the incorporation of somewhat smaller amounts of halogen-containing compounds in conjunction with organic peroxide compounds; as well as the incorporation, in combination with iron naphthenate, of chlorine compounds (e.g., chlorinated paraffins) in an amount sufficient to provide at least 2 percent by weight of chlorine content based upon the polymer composition. (See, for example, U.S. Pat. No. 3,595,815.) Unfortunately, however, such prior art approaches toward improved flammability characteristics generally carry with them attendant detrimental impact upon other important styrenic polymer foam properties such as decreased ultraviolet stability; decreased polymer stability (and thus increased degradation and decrease in foam strength); increased brittleness; foam discoloration; decreased heat distortion temperature, etc. and/or can introduce troublesome processing problems.
In view of the foregoing, it would be highly desirable to provide a means for improving the flammability characteristics of styrenic polymer foams while at the same time minimizing or at least significantly reducing aforementioned attendant disadvantages of the various prior art approaches.